title: Internal proton transfer and H2 rotations in the H5(+) cluster: a marked influence on its thermal equilibrium state.
abstract: Classical and path integral Monte Carlo (CMC, PIMC) "on the fly" calculations are carried out to investigate anharmonic quantum effects on the thermal equilibrium structure of the H5(+) cluster. The idea to follow in our computations is based on using a combination of the above-mentioned nuclear classical and quantum statistical methods, and first-principles density functional (DFT) electronic structure calculations. The interaction energies are computed within the DFT framework using the B3(H) hybrid functional, specially designed for hydrogen-only systems. The global minimum of the potential is predicted to be a nonplanar configuration of C(2v) symmetry, while the next three low-lying stationary points on the surface correspond to extremely low-energy barriers for the internal proton transfer and to the rotation of the H2 molecules, around the C2 axis of H5(+), connecting the symmetric C(2v) minima in the planar and nonplanar orientations. On the basis of full-dimensional converged PIMC calculations, results on the quantum vibrational zero-point energy (ZPE) and state of H5(+) are reported at a low temperature of 10 K, and the influence of the above-mentioned topological features of the surface on its probability distributions is clearly demonstrated.
authors.affiliation: Instituto de Física Fundamental, CSIC, Madrid, Spain.
authors.forename: Ricardo Pérez
authors.initials: RP
authors.lastname: de Tudela
authors.forename: Patricia
authors.initials: P
authors.lastname: Barragán
authors.forename: Rita
authors.initials: R
authors.lastname: Prosmiti
authors.forename: Pablo
authors.initials: P
authors.lastname: Villarreal
authors.forename: Gerardo
authors.initials: G
authors.lastname: Delgado-Barrio